This compound, (.+-.)3-deazaaristeromycin (compound VI), also known as (.+-.)-4-amino-1-[1.alpha.,2.beta.,3.beta.,4.alpha.)-2,3-dihydroxy-4-(hydr oxymethyl)cyclopentyl]-imidazo[4,5-c]pyridine, is a carbocyclic analog of adenosine and was found to inhibit adenosylhomocysteine hydrolase. Furthermore, it is noted that carbocyclic adenosine has no antiviral activity. Substitution of the 3-deazaadenine moiety for adenine in this compound gives a reversible inhibitor of the hydrolase more potent than 3-deazaadenosine and which has antiviral activity.